This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7119 from my application SHEET CONVEYING APPARATUS FOR AN IMAGE INFORMATION PROCESSOR filed with the Korean Industrial Property Office on Feb. 28, 2001 and there duly assigned Serial No. 10362/2001.
1. Technical Field
The present invention relates to image information processors such as printers, photocopiers, facsimiles, etc. and, more particularly, to a sheet conveying apparatus for an image information processor capable of enhancing accuracy as to skew-feed corrections through control of changing sheet-conveying speeds and also adjusting image resolutions.
2. Related Art
In general, image information processor such as printers, photocopiers, facsimiles, digital multifunction machines having functions of the mentioned devices, etc., convey image information-carrying sheets to an image reader by means of a sheet conveying apparatus having plural rotating rollers. The sheet conveying apparatus has the functions of aligning the leading ends of paper sheets and then correcting skew-feed.
A sheet conveying apparatus for a conventional image information processor includes a sheet separation roller and a sheet guide, oppositely mounted above and below, to separate plural paper sheets stacked on a sheet stacking plate one by one, and to convey the sheets to an image reader.
The image reader reads image information on the sheet through an image reading sensor, and converts an analog signal representing the read image information into a digital signal for output in a state wherein the image reader is elastically biased upwardly by a spring so as to be in close contact with a CS roller oppositely mounted at an upper portion, and the CS roller discharges the paper sheet from which the image reading is completed. A sheet presence/absence detection sensor senses the presence and absence of paper sheets loaded in the sheet stacking plate, and outputs information as to the sensed state as a signal, while a sheet leading end detection sensor senses the leading ends of paper sheets conveyed to the image reader, and outputs the sensed information as a signal.
The sheet leading end detection sensor outputs a control signal for matching an image reading area start point of a paper sheet with the time that the image reader starts to read in image information, and outputs a control signal to change the driving mode of a driving motor from a forward direction to a reverse direction, or vice versa, so as to interactively drive the sheet separation roller and the CS roller.
The sheet conveying apparatus for a conventional image information processor having the above structure, as disclosed in detail in U.S. Pat. No. 5,749,570 to Iwata et al., entitled SHEET CONVEYING APPARATUS issued on May 12, 1998, aligns the leading ends of paper sheets by using the changes of the forward and reverse directions of a driving motor and a mechanical timer mechanism (delay means) to thereby correct the skew-feed of the paper sheets.
Accordingly, there exists a problem in that the sheet conveying apparatus for the conventional image information processor having the above structure requires precision as to operational controls due to the complexity of the mechanism itself, and, in particular, the apparatus has difficulties in securing reliability with respect to precise control when supplying paper sheets at a high speed since the sheet conveying apparatus corrects the skew-feed of the sheets by instantly stopping, and then rotating the CS roller by using a mechanical timer mechanism.
Further, there exists a problem in that the conventional sheet conveying apparatus has difficulties in separately mounting a delivery roller for discharging paper sheets due to its structure. That is, in the case where the delivery roller is mounted, paper sheets are conveyed in the reverse direction since the delivery roller rotates in a reverse direction when the motor rotates in the reverse direction. Therefore, a problem occurs in that it becomes impossible to discharge paper sheets.
In addition, there is a further problem in that the conventional sheet conveying apparatus has its limitations as to the capacity and speed for processing image information since it is difficult to deliver sheets at a high speed with the exclusion of the delivery roller, the driving of which is controlled separately from the sheet separation roller and the CS roller.
The present invention has been developed to improve the sheet conveying apparatus for the above conventional image information processor in consideration of its problems, and thus it is an object of the present invention to provide a sheet conveying apparatus for an image information processor capable of enhancing accuracy as to skew-feed corrections through control of changing sheet conveying speeds and also adjusting image resolutions.
It is another object of the present invention to provide a sheet conveying apparatus for an image information processor which can be usefully employed to convey a large capacity of sheets at a high speed with an increased sheet discharge efficiency by mutually connecting and driving a driving unit for conveying sheets in selective combinations.
In order to achieve the above objects, a sheet conveying apparatus for an image information processor has a sheet conveying unit, disposed on a sheet conveying path provided between a sheet supply opening and a sheet discharge opening, for conveying a sheet in one direction, and a driving unit for driving the sheet conveying unit. The sheet conveying apparatus according to the present invention comprises the sheet conveying unit including a sheet separation roller, a sheet registration roller, a scan roller, and a sheet delivery roller disposed in order for rotation on the sheet conveying path. The driving unit includes a driving motor controlled to change driving modes thereof in the forward and reverse directions, and a driving device for receiving a driving force from the driving motor, and for selectively performing combined driving of the sheet separation roller, the sheet registration roller, the scan roller, and the sheet delivery roller in mutual operations thereof according to a sheet conveying process which utilizes a driving force of the driving motor.
According to the present invention, the driving unit preferably includes a power switching device for selectively transferring a rotational force to a first power transmission system or a second power transmission system according to the driving modes of the driving motor, a plurality of driving gears coaxially mounted on rotation shafts of the sheet separation roller, sheet registration roller, scan roller and sheet delivery roller for connection to the first and second power transmission systems, and a power cutoff unit for cutting off power by selectively restraining the driving gears mounted to the rotation shafts of the sheet separation roller and the sheet registration roller.
Further, the power switching device preferably includes first and second power switching gears connected to an output shaft of the driving motor, and first and second cam gears linearly movable in the rotation shaft directions of the first and second power switching gears so as to move forward and backward in opposite directions to each other according to the driving modes of the forward and reverse directions.